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Biomedical subjects

R J Aitken

Publications and source records attributed to R J Aitken.

At least 127 records · Page 7Linked to original sources
PubMed1992

Enhanced detection of reactive oxygen species produced by human spermatozoa with 7-dimethyl amino-naphthalin-1, 2-dicarbonic acid hydrazide.

A new chemiluminescence technique has been assessed for the detection of reactive oxygen species generated by purified populations of human sperm. This revised protocol involves the use of horse-radish peroxidase (HRP) in combination with a luminol analogue, 7-dimethyl amino-naphthalin-1,2-dicarbonic acid hydrazide (DNDH), that exhibits two-three times the quantal efficiency of luminol itself. The chemiluminescent signal generated with these reagents was significantly (P less than 0.001) greater than that obtained with the conventional luminol-based methodology for both the steady-state situation and following stimulation of the sperm with PMA and A23187. Dose-response analyses indicated that the DNDH/HRP chemiluminescence system could give linear standard curves with hydrogen peroxide concentrations into the nmol l-1 range. In contrast, the exponential rise in chemiluminescence recorded with luminol was not observed until hydrogen peroxide concentrations exceeded 10 mumol l-1. It is concluded that the enhanced sensitivity of the DNDH/HRP system to low levels of hydrogen peroxide should facilitate the application of chemiluminescent techniques to the diagnosis of oxidative stress in cases of male infertility.

Fluorescent Dyes↗
PubMed1992

Residual sperm function in oligozoospermia induced by testosterone enanthate administered as a potential steroid male contraceptive.

To investigate the fertility of men who remain oligozoospermic despite sex steroid suppression, the in-vitro fertilizing capacity of residual spermatozoa was assessed in 30 men receiving intramuscular testosterone enanthate (TE). Spermatozoa were prepared by either Percoll or repetitive centrifugation/washing. Although the mean (+/- SEM) pretreatment zona-free hamster oocyte penetration (HOP) rates were similar (59.4 +/- 10.1 and 63.8 +/- 10.8%), following the induction of oligozoospermia the Percoll-prepared spermatozoa exhibited a penetration rate (26.9 +/- 10.2%) which was markedly greater than that obtained for sperm prepared by repetitive washing (0 +/- 0%). In addition, the partners of two men exhibiting a HOP test with Percoll-prepared spermatozoa, conceived despite a sperm concentration of 3 x 10(6) ml-1 and a negative HOP test with spermatozoa prepared by repetitive washing. These results suggest that Percoll preparation optimizes the assessment of in-vitro sperm function and that the fertility of men with TE-induced severe oligozoospermia is suppressed but not abolished.

Adult↗
PubMed1992

Differential contribution of leucocytes and spermatozoa to the generation of reactive oxygen species in the ejaculates of oligozoospermic patients and fertile donors.

Cells isolated from the ejaculates of a high proportion of patients exhibiting oligozoospermia are characterized by generation rates of reactive oxygen species that considerably exceed those obtained for the normal fertile population. The purpose of this study was to resolve the cellular source of this enhanced activity. Semen samples from a cohort of oligozoospermic patients and a group of fertile controls were fractionated on discontinuous Percoll gradients to generate three cell populations (0, 50 and 100%) of differing density. For each fraction, both the steady-state and the phorbol-ester-induced chemiluminescent signals were significantly (P less than 0.001) greater for the oligozoospermic samples than for the fertile controls. In the fertile donors, leucocytes comprised the major source of reactive oxygen species, particularly in the low-density Percoll fractions; in oligozoospermic patients, however, spermatozoa were identified as a second major source of reactive oxygen species. Particularly striking was an intense phorbol-ester-induced chemiluminescent signal generated by oligozoospermic spermatozoa, purified by passage through isotonic Percoll and free of leucocyte contamination, which was 167 times greater than the median signal generated by the corresponding fraction from the fertile controls (P less than 0.001). These results emphasize the importance of spermatozoa as a major source of reactive oxygen species in oligozoospermia and have implications for the diagnosis and treatment of this condition, as well as for the design of appropriate diagnostic strategies.

Cell Separation↗
PubMed1991

Prospective analysis of sperm-oocyte fusion and reactive oxygen species generation as criteria for the diagnosis of infertility.

We have undertaken a prospective analysis of the diagnostic significance of three different criteria of human sperm function including the conventional semen profile, measurements of hamster-oocyte fusion, and determinations of reactive oxygen species generation in 139 couples. The latter, who were characterized by a lack of detectable abnormalities in the female partner, were followed up for a maximum of 4 years to determine the incidence of spontaneous pregnancy in the absence of therapeutic intervention. Assessments of monthly fecundity with life table analysis techniques revealed a highly significant, positive relationship between fertility and hamster-oocyte fusion rates that were measured in the presence of the ionophore, A23187. Conversely, reactive oxygen species generation was shown to be negatively associated with both the outcome of the sperm-oocyte fusion assay and fertility in vivo. The clinical significance of these diagnostic techniques was emphasized by the fact that within the same data set, the conventional semen profile was of no significant diagnostic value.

Animals↗
PubMed1991

Scale model studies of the transport of airborne pollutants on coalfaces.

Studies have been carried out to investigate airflows in coalmine models, with special regard to the transport of airborne pollutants, and to examine how they relate to what happens at full-scale in an actual underground mine. If such models can be shown to provide data representative of actual mine ventilation engineering, then they can provide cost-effective alternatives to full-scale investigations. The work set out in the first instance to identify the properties of: (a) the bulk airflow and associated transport of airborne pollutants along a longwall coalface; and (b) the transport of material out of regions that were partially enclosed or poorly ventilated (e.g. in the cutting zone, in headings). For the former, an appropriate quantity is the dispersivity of the coalface airflow, for the latter the mean retention time. Both quantities may be rendered non-dimensional with respect to dimensions characteristic of the system and to velocities of the airflow. Their behaviour in relation to a third dimensionless quantity, the flow Reynolds' number is also important. Experiments were performed, using smoke or dust tracers, to investigate how these properties are interrelated and how they scale between small-scale and full-scale systems. They were carried out in a 1/10-scale laboratory model, in a full-scale surface model, and underground in an actual coalmine. The basis of most of the experiments was the 'tracer decay' method, in which the transport properties of the aerodynamic system under investigation were determined from observations of the changes in tracer concentration with time immediately following the removal of the tracer source. During these experiments, the feasibility of using small-scale models to investigate ventilation problems was clearly indicated and preliminary scaling relationships which may be used as an initial basis for predicting the transport and local build-up of pollutants in mines were developed. It is expected that applications of the ideas and methodology described will be relevant to other industries.

Air Movements↗
PubMed1991

Non-palpable mammographic abnormalities.

The radiological characteristics of non-palpable mammographic abnormalities are reviewed and their diagnostic limitations discussed. Alternative methods of detection and diagnosis are reviewed. The development of needle localization for non-palpable mammographic abnormalities is traced from the initial crude excisions through to stereotactic needle localization. Non-palpable carcinomas have a greater proportion of favourable histopathologies. However, the preferred management of these early lesions has yet to be determined.

Biopsy, Needle↗
PubMed1990

Outcome of surgery for non-palpable mammographic abnormalities.

Four hundred and ninety-three women underwent 515 localization biopsies for non-palpable mammographic abnormalities. The mammographic abnormality was located with a hooked wire in 509 cases. Specimen radiology was performed on all excised tissue. The mammographic abnormality was visualized in the first piece of tissue excised in 402 (78.1 per cent) cases and complete excision was achieved in 476 (92.4 per cent). A palpable nodule was removed in 38 (7.4 per cent) cases and in 17 (44.7 per cent) was shown to contain a carcinoma. The mammographic abnormality was missed in 14 (2.7 per cent) cases or only partly excised in 13 (2.5 per cent). Overall 144 (28.0 per cent) localization biopsies were malignant. The mammographic abnormality was not visualized on the specimen radiograph more frequently in women aged under 55 years, in women with dense breast (Wolfe grade DM or DY) or in those whose mammographic abnormality contained only microcalcification. The 27 women in whom the mammographic abnormality was not visible on the specimen radiograph underwent repeat mammography 2 months later. Only two women required a further localization biopsy and the mammographic abnormality was recovered in the first piece of tissue excised. Women with a carcinoma underwent mastectomy or wide local excision, and residual carcinoma at the localization biopsy site was found in 64 (44.4 per cent) cases. Oestrogen receptor analysis by ligand binding assay was possible in only 71 (49.3 per cent) carcinomas. If the specimen radiograph does not show the mammographic abnormality within pieces of tissue excised and there is no palpable nodule it may be best to conclude the biopsy. In this series these missed lesions were usually benign. Only rarely is a second localization biopsy required and this is performed without difficulty.

Adult↗
PubMed1990

Analysis of sperm function in globozoospermia: implications for the mechanism of sperm-zona interaction.

The globozoospermic condition has provided a unique opportunity to determine how the abnormal mitochondrial organization and acrosomal loss associated with this syndrome, influence sperm function. Despite the abnormal midpiece architecture, the movement characteristics of the spermatozoa, in terms of the curvilinear, path, and progressive velocities, amplitude of head displacement, and hyperactivation were all within the normal range. Similarly, the behavior of the spermatozoa on Percoll gradients was normal, although the capacity of the isolated fractions to generate reactive oxygen species was negligible. Of particular significance was the fact that the globozoospermic spermatozoa were incapable of sperm-oocyte fusion or binding the human zona pellucida, even after an intracellular calcium signal had been generated with the ionophore A23187. The sudden induction of sperm-zona interaction could, however, be achieved by the use of a ferrous ion promoter system to induce limited lipoperoxidation. This result demonstrates that the enhancing effect of peroxidation on sperm-zona adhesion involves a direct action on the properties of the sperm-plasma membrane, rather than an indirect consequence of acrosomal damage and acrosin leakage. Such findings emphasize the value of specific teratozoospermic conditions, such as globozoospermia, in dissecting the mechanisms that regulate human sperm function.

Adult↗
PubMed1990

Evaluation of human sperm function.

Our understanding of the causes of male infertility and our ability to develop an appropriate range of diagnostic tests are both dependent upon a knowledge of the cellular mechanisms responsible for the regulation of human sperm function. This review examines the intra- and extracellular factors regulating four separate components of human sperm function: sperm transport, sperm-egg recognition, the acrosome reaction and sperm-oocyte fusion. Within each of these areas the fundamental nature of the process, the control mechanisms involved, the availability of appropriate diagnostic tests and the relationship with human infertility have been considered.

Acrosome↗
PubMed1990

The effect of iron and iron chelators on the in-vitro block to development of the mouse preimplantation embryo: BAT6 a new medium for improved culture of mouse embryos in vitro.

The effect of iron and iron chelators on the development of the mouse embryo in vitro from the 1-cell stage to the blastocyst has been investigated. An adverse effect of iron was found. The high affinity iron chelator, desferal, also blocked development, whilst transferrin (whether as apoprotein or saturated with iron), DETAPAC and EDTA promoted development. The addition of transferrin permitted development to the blastocyst stage of embryos from stains normally exhibiting the 2-cell block. Under such circumstances both the rate of embryonic development and the proportion of embryos reaching the blastocyst stage approached levels found in vivo. Based on these results, a new medium, BAT6, is described for the optimal in-vitro culture of mouse embryos.

Animals↗
PubMed1990

Analysis of the relationship between reactive oxygen species production and leucocyte infiltration in fractions of human semen separated on Percoll gradients.

We have shown previously that the reactive oxygen species generated by washed human ejaculates originate from cells which can be isolated in the low density region of discontinuous Percoll gradients. In this study we have used a simplified two-step (40/80%) Percoll gradient to separate human ejaculates (n = 109) into two populations of spermatozoa, exhibiting either a high or a low capacity for reactive oxygen species generation. We have then examined the relationships between this activity and other properties of the isolated fractions, with particular emphasis on the presence of leucocytes, which we have quantified using a monoclonal antibody directed against the common leucocyte antigen. The low-density cells recovered from the 40%/80% interface of the Percoll gradients, differed from the high-density fraction in exhibiting significantly reduced sperm motility, poorer sperm morphology, and a considerably enhanced capacity for reactive oxygen species production (P less than 0.001). In six cases the elevated levels of reactive oxygen species generation were associated with leucocyte concentrations in excess of 1 x 10(6) per 10(7) sperm, suggesting that leucocytes enter the seminal compartment in an activated, oxygen-radical generating, state. However, in the majority of cases exhibiting high levels of reactive oxygen species production, leucocyte numbers were low or absent and the semen profiles were unremarkable, except that seminal sperm concentrations tended to be low. These results suggest that the oxidative stress responsible for defective sperm function involves reactive oxygen species originating from two sources; the sperm and infiltrating leucocytes.

Cell Separation↗
PubMed1990

Mammography screening for breast cancer.

There is now unequivocal evidence that screening with mammography reduces the mortality of breast cancer. This benefit will best be realized by a national screening program. Such programs require a meticulous organization with dedicated staff who are experienced in the management of screen-detected lesions.

Adult↗
PubMed1989

Arm morbidity within a trial of mastectomy and either nodal sample with selective radiotherapy or axillary clearance.

The aim of this study was to assess upper limb morbidity following treatment for operable breast cancer. Patients were randomized to either mastectomy and axillary clearance (40 women: 12 with axillary nodal metastasis and 28 without axillary metastasis) or mastectomy and axillary sampling (54 women). Adjuvant radiotherapy was delivered to those in whom the sample revealed axillary nodal metastasis (28 women) but not to those with no axillary nodal metastasis (26 women). A subjective assessment of the state of the arm was made using a standard questionnaire. Objective assessment included upper and forearm circumference, should joint mobility and assessment of power in the pectoralis muscle. The mean age was 56.8 years (range 33-77 years) and the mean elapsed time from treatment was 5.72 years (range 4.0-7.5 years). Subjective limb oedema was greatest in those who had axillary lymph node metastasis but there was no objective difference. Subjective joint mobility was reduced in the women who received radiotherapy and this was confirmed by objective assessment (P less than 0.05). The objective reduction in arm mobility was related to the treatment rather than the axillary lymph node status. There was no difference in power. In this study women receiving adjuvant radiotherapy had significantly reduced shoulder mobility. This may have implications for current conservation studies using adjuvant radiotherapy.

Adult↗
PubMed1989

Lower limb vein trauma: a long-term clinical and physiological assessment.

The aim of this study was to assess the long-term clinical and physiological sequelae of lower limb venous trauma in a civilian practice. Twenty-six patients who had undergone surgery for lower limb venous trauma (median elapsed time 19.5 months) underwent assessment. Injuries had been sustained to the external iliac, common femoral superficial femoral and popliteal veins in two, four, nine and eleven limbs respectively. Using clinical assessment, photoplethysmography recovery time, the presence of popliteal reflux and venographic evidence of thrombosis, the final outcome was graded as good, fair or poor. Fourteen patients had pedal oedema, including two with a postphlebitic limb. The overall photoplethysmography recovery time (mean and s.d.) was 20.6 (8.7) s in the injured and 32.1 (6.7) s in the non-injured limbs (P = 0.002). Patients with a venographically occluded vein had a shorter photoplethysmography recovery time than those in whom the vein was patent (13.4 (5.6) versus 21.6 (8.7) s; P = 0.07). Popliteal reflux was present in 12 injured limbs. Seven of 12 venograms performed on limbs with a vein repair had evidence of previous thrombosis. Vein ligation carried considerable morbidity and all end-to-end anastomoses initially failed. In retrospect, saphenous vein grafts were too narrow for the recipient veins and panel grafts might have been more appropriate. Overall 11 of 26 patients (42 per cent) had a poor result. The repair of choice is a saphenous vein patch for lesser injuries and a saphenous panel graft for major injuries. Vein ligation should be avoided unless another life-threatening injury demands priority.

Adolescent↗
PubMed1989

Detection of Y-bearing spermatozoa by DNA-DNA in situ hybridisation.

In situ hybridisation of a Y chromosome-specific DNA probe to preparations of decondensed spermatozoa revealed approximately 46.7% labelled spermatozoa among 3,900 scored. This is not significantly different from the 50% expected if only the Y chromosome-bearing spermatozoa are hybridised. Control hybridizations of Escherichia coli DNA and salmon testis DNA to decondensed sperm produced no significant labelling, whereas more than 99% of the spermatozoa were heavily labelled after hybridisation to total human DNA. These controls indicate that the methodology described in this paper renders the chromatin accessible for hybridisation and that the 50% hybridisation observed with the Y chromosome DNA probe was specific. In situ hybridisation with the Y probe therefore identifies the Y-bearing spermatozoa, and the protocol described should prove useful in evaluating methods of separating Y-bearing and X-bearing spermatozoa.

Autoradiography↗
PubMed1989

Relationship between calcium, cyclic AMP, ATP, and intracellular pH and the capacity of hamster spermatozoa to express hyperactivated motility.

Capacitation of hamster caudal spermatozoa at a density of 1 x 10(6)/ml is associated with a progressive rise in cAMP levels that precedes the onset of hyperactivated motility. This increase is not expressed by caput spermatozoa incubated under identical conditions. Both the incidence of hyperactivation and the rise in cAMP levels are severely attenuated in the absence of exogenous calcium. Neither factor is restored to control levels by the addition of the phosphodiesterase inhibitor IBMX, although in the presence of exogenous calcium, this reagent increased cAMP levels, stimulated percentage motility and advanced the appearance of hyperactivation. Treatment of spermatozoa at a density of 1 x 10(6)/ml with the calmodulin antagonist, calmidazolium (CZ), caused severe disruption of sperm motility and abolished hyperactivation, while causing only a slight reduction in cAMP content. Addition of IBMX in the presence of CZ elevated cAMP content to levels higher than normally observed during capacitation but did not restore either coordinated or hyperactivated motility. To determine both the mechanisms responsible for this elevation of cAMP content and the changes that occur during epididymal maturation to facilitate the expression of this increase, the free cytosolic calcium concentration, ATP levels, and intracellular pH of caput and caudal cells were compared. The calcium content of caudal spermatozoa rose significantly at a time when cAMP levels were increasing, while ATP content and intracellular pH fell. However, the inability of caput spermatozoa to express a rise in cAMP content was not due to deficiencies in any of these factors. These results indicate a positive role for the cAMP rise in the expression of hyperactivated motility and that the fundamental control mechanism governing both these events may be the influx of calcium that accompanies capacitation in this species.

Adenosine Triphosphate↗